1. Field of the Invention
This invention relates to a method of manufacturing a semiconductor device having semiconductor formation regions of different planar sizes.
2. Description of the Related Art
As a semiconductor device installed in small-sized electronic equipment typified by, for example, portable electronic equipment, a chip size package (CSP) having about the same size (planar size and dimensions) as a semiconductor substrate has been known. Among the CSPs, there is one called a wafer level package (WLP) which is packaged in a wafer state and separated into semiconductor devices by dicing.
In such a conventional semiconductor device, as disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2004-349461, a wiring line is provided on the upper surface of an insulating film provided on a semiconductor substrate, a columnar electrode is provided on the upper surface of a connection pad portion of the wiring line, a sealing film is provided on the upper surface of the insulating film including the wiring line so that the upper surface of this sealing film is flush with the upper surface of the columnar electrode, and a solder ball is provided on the upper surface of the columnar electrode.
In the meantime, there is one such semiconductor device in which an interlayer insulating film/wiring line stack structure component comprising a stack structure composed of an interlayer insulating film and a wiring line is provided between a semiconductor substrate and an insulating film. In this case, if the distance between the wiring lines in the interlayer insulating film/wiring line stack structure component decreases in accordance with miniaturization, the capacity between the wiring lines increases, resulting in an increased delay of a signal transmitted through the wiring lines.
In order to improve this, a low dielectric constant material, called a low-k material, has been attracting attention as the material of the interlayer insulating film, in which the dielectric constant is lower than the dielectric constant of 4.2, to 4.0, of silicon oxide, which generally used as the material of the interlayer insulating film. The low-k material includes, for example, SiOC in which silicon oxide (SiO2) is doped with carbon (C), or SiOCH containing H. In order to further reduce the dielectric constant, an air-containing porous film with a low dielectric constant is also considered.
Presently, in a method of manufacturing a semiconductor device having a low dielectric constant film/wiring line stack structure component comprising a stack structure composed of a low dielectric constant film as an interlayer insulating film and a wiring line, the low dielectric constant film and the wiring line are stacked and formed on a semiconductor substrate in a wafer state, and an insulating film, an upper wiring line, a columnar electrode, a sealing film and a solder ball are formed thereon, which are then separated into semiconductor devices by dicing.
However, if the low dielectric constant film is cut with a dicing blade, a large amount of cutoff portions and damage are caused in the cut surface of the low dielectric constant film due to the fragility of the low dielectric constant film. Thus, one method under consideration is to remove a part, which corresponds to a dicing street, of the low dielectric constant film formed on the semiconductor substrate in a wafer state at a relatively early stage by the application of a laser beam together with a passivation film which is formed on this part and which is made of an inorganic material such as silicon nitride.
However, in the semiconductor device manufacturing method which removes a part, which corresponds to the dicing street, of the low dielectric constant film formed on the semiconductor substrate in a wafer state at a relatively early stage by the application of a laser beam together with a passivation film which is formed on this part, missing portions may be generated from the surface removed by the application of the laser beam due to low strength of close contact between the low dielectric constant film in this removed surface and the passivation film. Such missing portions could cause problems in the subsequent steps.